add mp3 player code

Code/MP3Player/pico_mp3_player.cpp

@@ -0,0 +1,25 @@
+/////////////////////////////
+// MP3 player for RPi Pico //
+/////////////////////////////
+//
+// main() only starts the multitasking and
+// runs the main task (see main_task.h/cpp)
+//
+#include <cstdio>
+#include "main_task.h"
+#include "uart_rp2040.h"
+#include "posix_io.h"
+int main()
+{
+    uart_rp2040 uart;
+    posix_io::inst.register_stdin ( uart );
+    posix_io::inst.register_stdout( uart );
+    posix_io::inst.register_stderr( uart );
+
+    task::sleep_ms(2000);//really neccessary form uart debug
+    // Start Main task as privileged task
+    main_task Main;
+    Main.start(MAIN_PRIORITY, true);
+    // Start the multitasking
+    task::start_scheduler();
+}